According to his own testimony, Kennedy accidentally drove his car off a bridge and into the channel, before swimming free and leaving the scene, and not reporting about the accident for nine hours. Meanwhile, Kopechne had died in the car through drowning or suffocation. The next day, Kopechne's body and the car were finally recovered. Kennedy pleaded guilty to a charge of leaving the scene of an accident after causing injury and later received a two-month suspended jail sentence. The incident became a national scandal, and may have influenced Kennedy's decision not to campaign for President of the United States in 1972 and 1976.

According to his own testimony at the inquest into Kopechne's death, Kennedy left the party at "approximately 11:15 p.m."[4] He said that when he announced that he was about to leave, Kopechne told him "that she was desirous of leaving, if I would be kind enough to drop her back at her hotel." Kennedy then requested the keys to his mother's car from his chauffeur, Crimmins. Asked why he did not have his chauffeur drive them both, Kennedy explained that Crimmins along with some other guests "were concluding their meal, enjoying the fellowship and it didn't appear to me necessary to require him to bring me back to Edgartown".[5] Kopechne told no one that she was leaving with Kennedy, and left her purse and hotel key at the party.[6]

Christopher "Huck" Look was a deputy sheriff working as a special police officer at the Edgartown regatta dance that night. At 12:30 a.m., he left the dance, crossed over to Chappaquiddick in the yacht club's launch boat, got into his parked car and drove toward his home, which was south of the Dike Bridge. He testified that between 12:30 and 12:45 a.m. he had seen a dark car containing a man driving and a woman in the front seat approaching the intersection with Dike Road. The car had gone first onto the private Cemetery Road and stopped there. Thinking that the occupants of the car might be lost, Look had gotten out of his car and walked toward it. When he was 25 to 30 feet away, the car started backing towards him. When Look called out to offer his help, the car moved quickly eastward, towards the ocean, along Dike Road in a cloud of dust.[7] Look recalled that the car's license plate began with an "L" and contained two "7"'s, both details true of Kennedy's 1967 Oldsmobile Delmont 88; the license plate on Kennedy's vehicle was "L78-207".

According to his inquest testimony, Kennedy made a wrong turn onto Dike Road, an unlit dirt road that led to Dike Bridge (also spelled Dyke Bridge). Dike Road was unpaved, but Kennedy, driving at "approximately twenty miles an hour", took "no particular notice" of this fact, and did not realize that he was no longer headed toward the ferry landing.[8] Dike Bridge was a wooden bridge angled obliquely to the road, with no guardrail. A fraction of a second before he reached the bridge, Kennedy applied his brakes; he then drove over the side of the bridge. The car plunged into tide-swept Poucha Pond (at that location a channel) and came to rest upside-down underwater. Kennedy recalled later that he was able to swim free of the vehicle, but Kopechne was not. Kennedy claimed at the inquest that he called Kopechne's name several times from the shore, then tried to swim down to reach her seven or eight times, then rested on the bank for around fifteen minutes before returning on foot to Lawrence Cottage, where the party attended by Kopechne and the other "Boiler Room Girls" had occurred. Kennedy denied seeing any house with a light on during his journey back to Lawrence Cottage.[9]

"Dike House" along Dike Road

In addition to the working telephone at the Lawrence Cottage, according to one commentator, his route back to the cottage would have taken him past four houses from which he could have telephoned and summoned help; however, he did not do so.[10] The first of those houses, referred to as "Dike House", was 150 yards away from the bridge, and was occupied by Sylvia Malm and her family at the time of the incident. Malm stated later that she had left a light on at the residence when she retired for that evening.[11]

According to Kennedy's testimony, Gargan and party co-host Paul Markham then returned to the waterway with Kennedy to try to rescue Kopechne. Both of the other men also tried to dive into the water and rescue Kopechne multiple times.[2] When their efforts to rescue Kopechne failed, Kennedy testified, Gargan and Markham drove with Kennedy to the ferry landing, both insisting multiple times that the accident had to be reported to the authorities.[12] According to Markham's testimony Kennedy was sobbing and on the verge of becoming crazed.[13] Kennedy went on to testify that "[I] had full intention of reporting it. And I mentioned to Gargan and Markham something like, 'You take care of the other girls; I will take care of the accident!'—that is what I said and I dove into the water".[12] Kennedy had already told Gargan and Markham not to tell the other women anything about the incident "[b]ecause I felt strongly that if these girls were notified that an accident had taken place and Mary Jo had, in fact, drowned, that it would only be a matter of seconds before all of those girls, who were long and dear friends of Mary Jo's, would go to the scene of the accident and enter the water with, I felt, a good chance that some serious mishap might have occurred to any one of them".[14] Gargan and Markam would testify that they assumed that Kennedy was going to inform the authorities once he got back to Edgartown, and thus did not do so themselves.[3]

According to his own testimony, Kennedy swam across the 500-foot channel, back to Edgartown and returned to his hotel room, where he removed his clothes and collapsed on his bed.[14] Hearing noises, he later put on dry clothes and asked someone what the time was: it was something like 2:30 a.m., the senator recalled. He testified that, as the night went on, "I almost tossed and turned and walked around that room ... I had not given up hope all night long that, by some miracle, Mary Jo would have escaped from the car."[15]

Back at his hotel, Kennedy complained at 2:55 a.m. to the hotel owner that he had been awoken by a noisy party.[3] By 7:30 a.m. the next morning he was talking "casually" to the winner of the previous day's sailing race, with no indication that anything was amiss.[3] At 8 a.m., Gargan and Markham joined Kennedy at his hotel where they had a "heated conversation." According to Kennedy's testimony, the two men asked why he had not reported the accident. Kennedy responded by telling them "about my own thoughts and feelings as I swam across that channel ... that somehow when they arrived in the morning that they were going to say that Mary Jo was still alive".[15] The three men subsequently crossed back to Chappaquiddick Island on the ferry, where Kennedy made a series of telephone calls from a pay telephone near the crossing. The telephone calls were to his friends for advice and again, he did not report the accident to authorities.[3]

Earlier that morning, two amateur fishermen had seen the submerged car in the water and notified the inhabitants of the cottage nearest to the scene, who called the authorities at about 8:20 a.m.[16]

Edgartown Police Chief James Arena arrived at the scene about 10 or 15 minutes later.[17] After attempting unsuccessfully to examine the interior of the submerged vehicle,[17][18] Arena summoned a professional diver, along with equipment capable of towing or winching the vehicle out of the water.[19] The diver, John Farrar, arrived at 8:45 fully suited in scuba gear, discovered Kopechne's body and extricated it from the vehicle within ten minutes.[20][21] Police checked the car's license plate and saw that it was registered to Kennedy.[2] When Kennedy, still at the payphone by the ferry crossing, heard that the body had been discovered, he crossed back to Edgartown and went to the police station; Gargan simultaneously went to the hotel where the "boiler room girls" were staying to inform them about the incident.[3]

At 10 am Kennedy entered the police station in Edgartown, made a couple of telephone calls, then dictated a statement to his aide Paul Markham, which was then given to the police. The statement was as follows:

On July 18, 1969, at approximately 11:15 p.m. in Chappaquiddick, Martha's Vineyard, Massachusetts, I was driving my car on Main Street on my way to get the ferry back to Edgartown. I was unfamiliar with the road and turned right onto Dike Road, instead of bearing hard left on Main Street. After proceeding for approximately one-half mile on Dike Road I descended a hill and came upon a narrow bridge. The car went off the side of the bridge. There was one passenger with me, one Miss Mary [Kopechne],[22] a former secretary of my brother Sen. Robert Kennedy. The car turned over and sank into the water and landed with the roof resting on the bottom. I attempted to open the door and the window of the car but have no recollection of how I got out of the car. I came to the surface and then repeatedly dove down to the car in an attempt to see if the passenger was still in the car. I was unsuccessful in the attempt. I was exhausted and in a state of shock. I recall walking back to where my friends were eating. There was a car parked in front of the cottage and I climbed into the backseat. I then asked for someone to bring me back to Edgartown. I remember walking around for a period and then going back to my hotel room. When I fully realized what had happened this morning, I immediately contacted the police.[23]

On July 25, seven days after the incident, Kennedy pleaded guilty to a charge of leaving the scene of an accident after causing injury. Kennedy's attorneys suggested that any jail sentence should be suspended, and the prosecutors agreed to this, citing Kennedy's age, character and prior reputation.[24] Judge James Boyle sentenced Kennedy to two months' incarceration, the statutory minimum for the offense, which he suspended. In announcing the sentence, Boyle referred to Kennedy's "unblemished record" and said that he "has already been, and will continue to be punished far beyond anything this court can impose".[25]

At 7:30 p.m. that evening Kennedy made a lengthy prepared statement about the incident which was broadcast live by the television networks. Among other things, he said that:[26]

"Only reasons of health" had prevented his wife from accompanying him to the regatta.

There was "no truth whatever to the widely circulated suspicions of immoral conduct" regarding Kennedy's and Kopechne's behavior that evening.

He "was not driving under the influence of liquor".

His conduct during the hours immediately after the accident "made no sense to [him] at all".

His doctors had informed him that he had suffered cerebral concussion and shock, but he did not seek to use his medical condition to escape responsibility for his actions.

He "regard[ed] as indefensible that fact that [he] did not report the accident to the police immediately."

Instead of notifying the authorities immediately, Kennedy "requested the help of two friends, Joe Gargan and Paul Markham, and directed them to return immediately to the scene with [him] (it then being sometime after midnight) in order to undertake a new effort to dive down and locate Miss Kopechne".

"All kinds of scrambled thoughts" went through his mind after the accident, including "whether the girl might still be alive somewhere out of that immediate area," "whether some awful curse actually did hang over all the Kennedys", "whether there was some justifiable reason for [him] to doubt what had happened and to delay [his] report", and "whether somehow the awful weight of this incredible incident might in some way pass from [his] shoulders".

He was overcome "by a jumble of emotions—grief, fear, doubt, exhaustion, panic, confusion and shock".

Having instructed Gargan and Markham "not to alarm Mary Jo's friends that night", Kennedy returned to the ferry with the two men, and then "suddenly jumped into the water and impulsively swam across, nearly drowning once again in the effort, returning to [his] hotel around 2 a.m. and collapsed in [his] room".

Kennedy then asked the people of Massachusetts to decide whether he should resign:

If at any time, the citizens of Massachusetts should lack confidence in their Senator’s character or his ability, with or without justification, he could not in my opinion adequately perform his duties, and should not continue in office. The opportunity to work with you and serve Massachusetts has made my life worthwhile. So I ask you tonight, the people of Massachusetts, to think this through with me. In facing this decision, I seek your advice and opinion. In making it I seek your prayers. For this is a decision that I will have finally to make on my own.[4]

John Farrar, the diver who recovered Kopechne's body and captain of the Edgartown Fire Rescue unit, asserted that Kopechne did not die from the vehicle overturn or from drowning, but rather from suffocation, based upon the posture in which he found the body and its position relative to the area of an ultimate air pocket in the overturned vehicle. Farrar also asserted that Kopechne would likely have survived had a more timely attempt at rescue been conducted.[28] Farrar located Kopechne's body in the well of the backseat of the overturned submerged car. Rigor mortis was apparent and her hands were clasping the backseat and her face was turned upward.[29] Farrar testified at the Inquest:

It looked as if she were holding herself up to get a last breath of air. It was a consciously assumed position. ... She didn't drown. She died of suffocation in her own air void. It took her at least three or four hours to die. I could have had her out of that car twenty-five minutes after I got the call. But he [Ted Kennedy] didn't call.

— diver John Farrar, Inquest into the Death of Mary Jo Kopechne, Commonwealth of Massachusetts, Edgartown District Court. New York: EVR Productions, 1970.

Farrar testified later at the inquest that Kopechne's body was pressed up in the car in the spot where an air bubble would have formed. He interpreted this to mean that Kopechne had survived in the air bubble after the accident, and concluded that

Had I received a call within five to ten minutes of the accident occurring, and was able, as I was the following morning, to be at the victim's side within twenty-five minutes of receiving the call, in such event there is a strong possibility that she would have been alive on removal from the submerged car.[10]

Farrar believed that Kopechne "lived for at least two hours down there."[30]

The deceased wore a blouse, bra, and slacks, but no panties.[31] The medical examiner, Dr. Donald Mills, was satisfied that the cause of death was accidental drowning. He signed a death certificate to that effect and released Kopechne's body to her family without ordering an autopsy and Kopechne was buried just a day after dying.[32] Later, on September 18, District Attorney Edmund Dinis attempted to secure an exhumation of Kopechne's body in order to perform a belated autopsy,[33] citing blood found on Kopechne's long-sleeved blouse and in her mouth and nose "which may or may not be consistent with death by drowning".[34] The reported discovery of the blood was made when her clothes were given to authorities by the funeral director.[35]

Judge Bernard Brominski, of the Court of Common Pleas of Luzerne County, Pennsylvania, had a hearing on the request on October 20–21.[33] The request was opposed by Kopechne's parents.[33] Forensic pathologist Werner Spitz testified on behalf of Joseph and Gwen Kopechne that the autopsy was unnecessary and the available evidence was sufficient to conclude that Kopechne died from drowning.[36][37] Eventually Judge Brominski ruled against the exhumation on December 10, saying that there was "no evidence" that "anything other than drowning had caused the death of Mary Jo Kopechne".[38]

The inquest into Kopechne's death occurred in Edgartown in January 1970. At the request of Kennedy's lawyers, the Massachusetts Supreme Judicial Court ordered that it be performed secretly.[39][40] The 763-page transcript of the inquest was released four months later.[40] Judge James A. Boyle presided at the inquest. Among Judge Boyle's conclusions in his inquest report were the following:[41]

The accident occurred "between 11:30 p.m. on July 18 and 1:00 a.m. on July 19".

"Kopechne and Kennedy did not intend to drive to the ferry slip and his turn onto Dike Road had been intentional".

"A speed of twenty miles per hour as Kennedy testified to operating the car as large as his Oldsmobile would be at least negligent and possibly reckless."

"For some reason not apparent from [Kennedy]'s testimony, he failed to exercise due care as he approached the bridge."

"There is probable cause to believe that Edward M. Kennedy operated his motor vehicle negligently ... and that such operation appears to have contributed to the death of Mary Jo Kopechne."

Under Massachusetts law, Boyle, having found "probable cause" that Kennedy had committed a crime, could have issued a warrant for his arrest, but he did not do so.[42] District Attorney Dinis chose not to prosecute Kennedy for manslaughter, despite Judge Boyle's conclusions.

The Kopechne family did not bring any legal action against Senator Kennedy, but they did receive a payment of $90,904 from the Senator personally and $50,000 from his insurance company.[43] The Kopechnes later explained their decision to not take legal action by saying that "We figured that people would think we were looking for blood money."[43]

On April 6, 1970, Dukes Countygrand jury assembled in special session to consider Kopechne's death. Judge Wilfred Paquet instructed the members of the grand jury that they could consider only those matters brought to their attention by the superior court, the district attorney or their own personal knowledge.[44] Citing the orders of the Massachusetts Supreme Judicial Court, Paquet told the grand jury that it could not see the evidence or Judge Boyle's report from the inquest (which at that time were still impounded).[44] District Attorney Dinis, who had attended the inquest and seen Judge Boyle's report, told the grand jury that there was not enough evidence to indict Senator Kennedy on potential charges of manslaughter, perjury or driving to endanger.[44] The grand jury called four witnesses who had not testified at the inquest: they testified for a total of 20 minutes, but no indictments were issued.[44]

On July 23, 1969, the Registrar of the Massachusetts Registry of Motor Vehicles informed Senator Kennedy that his license would be suspended until a statutory hearing could be held concerning the accident.[45] This suspension was required by Massachusetts law for any fatal motor accident where there were no witnesses. The in camera hearing was held May 18, 1970. It found that "operation was too fast for existing conditions". On May 27 the Registrar informed Sen. Kennedy in a letter that "I am unable to find that the fatal accident in which a motor vehicle operated by you was involved, was without serious fault on your part", and that as a result, his driver's license was suspended for a further six months.[46]

Sen. Kennedy's wife Joan Bennett Kennedy was pregnant at the time of the incident. Though confined to bed because of two previous miscarriages, she attended the funeral of Kopechne and stood beside her husband in court three days later.[47] She suffered a third miscarriage soon thereafter[48] which she blamed on the Chappaquiddick incident.[49]

A BBC Inside Story episode, "Chappaquiddick", broadcast on the 25th anniversary of the death of Mary Jo Kopechne advanced a theory that Kennedy and Kopechne had gone out from the party in Kennedy's car, but that when Kennedy saw an off-duty policeman in his patrol car, he got out of the car, fearing the political consequences of being discovered by the police late at night with an attractive woman. According to the theory, Kennedy then returned to the party while Kopechne, unfamiliar both with the large car and the local area, drove the wrong way and crashed off the bridge. The episode argued this explanation would account for Kennedy's lack of concern the next morning (because he was unaware of the crash) and for forensic evidence of the injuries to Kopechne being inconsistent with her sitting in the passenger seat.[50]

Best-selling investigative writer Jack Olsen had earlier advanced a similar theory in his book The Bridge at Chappaquiddick, published early in 1970. Olsen's book was the first full-length examination of the case. Olsen wrote that Kopechne's shorter height (she was 5'2", a foot shorter than Kennedy) could have accounted for her possibly not even seeing the bridge as she drove Kennedy's car over unfamiliar roads, at night, with no external lighting, after having had several alcoholic drinks at the party both had attended. Olsen wrote that Kopechne normally drove a smaller Volkswagen model car, which was much lighter and easier to handle than Kennedy's larger Oldsmobile.[19]

The case resulted in much satire of Kennedy, including a mock advertisement in National Lampoon magazine showing a floating Volkswagen Beetle with the remark that Kennedy would have been elected president had he been driving a Beetle that night; this satire resulted in legal action by Volkswagen, claiming unauthorized use of its trademark.[51]National Lampoon also printed a fake quote from Kennedy, as a "response" to a question on whether he planned to campaign for President in the next election: "I'll drive off that bridge when I come to it."

After Kennedy's televised speech on July 25, 1969, regarding the incident, telephone calls and telegrams to newspapers and to the Kennedy family were heavily in favor of his remaining in office, and he won reelection the next year with 62% of the vote. Nonetheless, the incident severely damaged his national reputation. Before Chappaquiddick, public polls showed that a large majority expected Kennedy to run for the presidency in 1972. After the incident, he pledged not to run in 1972 and declined to serve as George McGovern's running mate that year. In 1974, he pledged not to run in 1976, in part because of the renewed media interest in Chappaquiddick.[6]

Kennedy finally announced his candidacy for the American presidency in late 1979, challenging incumbent President Jimmy Carter for the Democratic nomination for the 1980 election. On November 4, 1979, CBS broadcast a one-hour television special presented by Roger Mudd titled Teddy. The program consisted of an interview with Kennedy, interspersed with visual materials. Much of the show was devoted to the Chappaquiddick incident. During the interview, Mudd questioned Kennedy repeatedly about the incident and at one point accused him directly of lying.[52] During the interview, Kennedy also gave what one author described as an "incoherent and repetitive" answer to the question, "Why do you want to be President?",[53] and called the American-supported Shah of Iran "one of the most violent regimes in the history of mankind".[54] The program inflicted serious political damage on Kennedy.[53][54][55][56][57] Carter alluded to the Chappaquiddick incident twice in five days, once declaring that he had not "panicked in the crisis."[58] Kennedy lost the Democratic nomination to Carter, but remained a Senator until his death in 2009.

After Kennedy's death, Ed Klein, an editor for New York Times Magazine and an author of several books about the Kennedy family, stated that Kennedy asked people he met, "Have you heard any new jokes about Chappaquiddick?" Klein also said, "It’s not that he didn’t feel remorse about the death of Mary Jo Kopechne, but that he still always saw the other side of everything and the ridiculous side of things, too."[59]

Rust, Zad (1971). Teddy Bare: The Last of the Kennedy Clan. Boston: Western Islands. OCLC147764. This book follows the circumstances of the Chappaquiddick tragedy, from its mysterious beginning to its squalid conclusion ... before a terrorized grand jury...." -- Prologue to the book, p. vii